submodules: bump external/sapphire-paratime from 06fe637 to d88a826

Bumps [external/sapphire-paratime](https://github.com/oasisprotocol/sapphire-paratime) from `06fe637` to `d88a826`.
- [Release notes](https://github.com/oasisprotocol/sapphire-paratime/releases)
- [Commits](oasisprotocol/sapphire-paratime@06fe637...d88a826)

---
updated-dependencies:
- dependency-name: external/sapphire-paratime
  dependency-type: direct:production
...

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